/*
 moxl - Modular XML Library
 Copyright (c) 2007, Malcolm Sparks

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package moxl.xpath.parser.states.locationpath;

import moxl.tokenizer.Token;
import moxl.tokenizer.TokenStream;
import moxl.xpath.parser.XPathParser;
import moxl.xpath.parser.XPathParserException;
import moxl.xpath.parser.states.XPathParserState;
import moxl.xpath.parser.types.NonTerminal;
import moxl.xpath.parser.types.PathExpression;
import moxl.xpath.parser.types.Step;
import moxl.xpath.tokenizer.XPathTokenTypes;

public class XPathLocationPathStartState extends XPathParserState
{
	private static XPathParserState instance = new XPathLocationPathStartState();

	public static XPathParserState getInstance()
	{
		return instance;
	}

	@Override
	public boolean isStartState()
	{
		return true;
	}

	@Override
	public void acceptAxisName(XPathParser ctx, TokenStream tstream, Token token, NonTerminal nonTerminal) throws XPathParserException
	{
		tstream.pushback(token);
		XPathParser stepParser = ctx.begetParser();
		Step step = stepParser.parseStepFromStream(tstream);
		PathExpression locationPath = (PathExpression) nonTerminal;
		locationPath.addStep(step);
		Token lookahead = lookahead(tstream, 1);
		if (lookahead != null && lookahead.getType().equals(XPathTokenTypes.OPERATOR) && lookahead.getImage().startsWith("/"))
		{
			ctx.changeState(XPathLocationPathExpectingStepSeparatorState.getInstance());
		}
		else
		{
			ctx.changeState(XPathLocationPathEndState.getInstance());
		}
	}

	/**
	 * This indicates a location path, starting with an abbreviated axis specifier
	 */
	@Override
	public void acceptAtSymbol(XPathParser ctx, TokenStream tstream, Token token, NonTerminal nonTerminal) throws XPathParserException
	{
		acceptAxisName(ctx, tstream, token, nonTerminal);
	}

	/**
	 * This indicates an implied child::
	 */
	@Override
	public void acceptNameTest(XPathParser ctx, TokenStream tstream, Token token, NonTerminal nonTerminal) throws XPathParserException
	{
		acceptAxisName(ctx, tstream, token, nonTerminal);
	}

	@Override
	public void acceptOperator(XPathParser ctx, TokenStream tstream, Token token, NonTerminal nonTerminal) throws XPathParserException
	{
		if (token.getImage().equals("/"))
		{
			throw new XPathParserException("This XPath parser does not yet support absolute location paths.");
		}
		else
		{
			super.acceptOperator(ctx, tstream, token, nonTerminal);
		}
	}
	
	@Override
	public void acceptNodeType(XPathParser ctx, TokenStream tstream, Token token, NonTerminal nonTerminal) throws XPathParserException 
	{
		acceptAxisName(ctx, tstream, token, nonTerminal);
	}


}
